1966 427 425HP Valve Clearances - NCRS Discussion Boards

1966 427 425HP Valve Clearances

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  • Joe L.
    Beyond Control Poster
    • February 1, 1988
    • 43193

    #31
    Re: 1966 427 425HP Valve Clearances

    Originally posted by Jack Cox (7670)
    Thanks to you both. A friend of mine knows the well known engine builder in my area (Mike Kodenko in Santa Paula, CA) and called him about this issue and before my friend could say anything other than 427 Mike said flat cam, yeah, we're having problems with all of them right now. Are Sealed Power, Comp, Crane, etc., all getting stock from China and it's all junk steel now? I can give up on Comp Cams and go with Sealed Power but it's sounding like it's a wing and a prayer crap-shoot either way. I'll re-post after I have a chance to talk to Mike and see if he has a solution at best or his recommendations at the least.

    Jack-------


    For many years most aftermarket and many OEM camshaft cores were manufactured by CWC, a division of Textron. The headquarters and main foundry of CWC is in Muskegon, MI. As far as I know, they still manufacture camshaft cores. However, like most companies and, especially, foundries, a lot of production has shifted to China. That, by itself, does not mean the products are bad----much OEM manufacture now occurs in China.
    In Appreciation of John Hinckley

    Comment

    • Chris H.
      Very Frequent User
      • April 1, 2000
      • 837

      #32
      Re: 1966 427 425HP Valve Clearances

      Jack, my L71’s original OEM flat tapper cam lobes wore down significantly. So after much research and analysis I’ve decided to go with a hydraulic roller cam. Modern grinds make more power under the curve and there’s no more worrying about ZDDP. I’d bring it up with your engine builder.
      1969 Riverside Gold Coupe, L71, 14,000 miles. Top Flight, 2 Star Bowtie.

      Comment

      • Jack C.
        Frequent User
        • June 30, 1984
        • 48

        #33
        Re: 1966 427 425HP Valve Clearances

        Chris - I've considered the hydraulic roller option, also recommended by another very experienced engine builder friend of mine. I'm not a novice, but these two guys are the proverbial forgot more than I'll ever know type of guys. Obviously it won't have that factory solid lifter sound for the purist (or for judging) but I drive my cars and I want to drive this one as well. I did not want to do this twice, and I sure don't want to do it three times. If much of what is available for flat tappet today is a high percentage failure rate I will go another direction out of necessity and forget the originality on this part of the build.

        It sounds like you have made the decision but have not acted yet? Have you identified a hydraulic roller cam with at least a similar to factory spec grind?

        Comment

        • James G.
          Very Frequent User
          • August 22, 2018
          • 783

          #34
          Re: 1966 427 425HP Valve Clearances

          I had a custom solid roller designed for a 302 SB by Dave Crower at Crower Cams, he told me that running a solid roller on the street requires a HIPPO lifter (high performance pin oiled).
          James A Groome
          1971 LT1 11130 - https://photos.app.goo.gl/zSoFz24JMPXw5Ffi9 - the black LT1
          1971 LT1 21783 - 3 STAR Preservation.- https://photos.app.goo.gl/wMRDJgmyDyAwc9Nh8 - Brandshatch Green LT1
          My first gen Camaro research http://www.camaros.org/forum/index.p...owposts;u=4337
          Posts on Yenko boards... https://www.yenko.net/forum/search.php?searchid=826453

          Comment

          • Jack C.
            Frequent User
            • June 30, 1984
            • 48

            #35
            Re: 1966 427 425HP Valve Clearances

            Originally posted by James Groome (65120)
            I had a custom solid roller designed for a 302 SB by Dave Crower at Crower Cams, he told me that running a solid roller on the street requires a HIPPO lifter (high performance pin oiled).
            Thanks, I was hoping for an off-the-shelf solution rather then re-inventing the wheel here. Obviously I don't have the only engine of late with this issue. I'll be doing research and I'll post back what I learn.

            Comment

            • Chris H.
              Very Frequent User
              • April 1, 2000
              • 837

              #36
              Re: 1966 427 425HP Valve Clearances

              Jack, the challenge with C3s is that we need lots of vacuum (At least 10 inches) to
              run headlight and wiper doors etc. So cam selection needs to factor in compression ratio, max rpm and vacuum. I haven’t selected a cam yet but I have decided to go with 10.0:1 compression ratio versus 11.1 factory. 11.1 rollers just don’t generate enough vacuum and there is very limited cam selection.
              1969 Riverside Gold Coupe, L71, 14,000 miles. Top Flight, 2 Star Bowtie.

              Comment

              • Jack C.
                Frequent User
                • June 30, 1984
                • 48

                #37
                Re: 1966 427 425HP Valve Clearances

                Chris, I have two C3s, a 69 350/350 Top Flight convertible that runs and drives beautifully and all the vacuum devices work properly as well. When I rebuild this car 11:1 forged pistons were still available. I used a FM cam (I don't have the specific number available at the moment) that was supposed to match the factory 350/350 grind. 2,000 miles + and no cam issues. The other C3 is a 70 LT-1. I also installed a FM cam in this car (may have been Sealed Power by then, and again I'd have to look up the number). Again, supposed to match the factory grind. This car is not complete yet so I cannot attest to any vacuum issues, but again, it should be as factory. I have, however, run the engine through the cam break in period and re-checked valve lash and adjusted carburetion and this engine sounds great. As a side note, I stayed with 11:1 pistons with this car as well but by the time I did this engine forged pistons were no longer available (I wasn't going to get custom made) so I went with hypereutectic pistons.

                In researching I found the article below. Of course, in the specs, how to, and final performance numbers there is no mention of vacuum. I could probably find out, however. My cousin worked at Hot Rod for years and knows the article writer, Jeff Smith, very well. Or, if I end up going with this cam setup, I'll let you know the vacuum numbers on my L72. The most surprising thing to me in the article was the relatively low RPM at max HP. To me that translates to better low RPM vacuum, but I don't know how you know until you run it. Like I said, Duke may be right on his recommendations against Comp, but my trusted sources are telling me this is an issue across the board. I'm a purist but... I have to work within the reality of the day. I'd appreciate any feedback on the option presented in the link below.

                Words And Photos: Jeff Smith In acting, timing is everything. The same could be said for performance engines. But instead of ignition timing, let’s talk about valve timing. While opening and closing points are critical, the secret to a strong performance valve lift curve is the aggressive combination of lift …

                Comment

                • Chris H.
                  Very Frequent User
                  • April 1, 2000
                  • 837

                  #38
                  Re: 1966 427 425HP Valve Clearances

                  Jack, interesting article. Differences include longer stroke and oval port heads when compared to L71/72. There are really an infinite amount of cam choices out there including custom grinds. I’ve looked at a lot of cam catalogues and see trends for big Chevys using hydraulic rollers which I will dig up.
                  1969 Riverside Gold Coupe, L71, 14,000 miles. Top Flight, 2 Star Bowtie.

                  Comment

                  • Chris H.
                    Very Frequent User
                    • April 1, 2000
                    • 837

                    #39
                    Re: 1966 427 425HP Valve Clearances

                    For reference, the Chevy Performance catalogue, which contains all their crate motors etc., has the ZZ427/480, which is marketed as a "modern take on the classic L88". It has 10.0:1 compression, oval port aluminum heads, and the cam is a hydraulic roller, 224/234 with 527/544 ex lift. LSA not listed. 480HP @ 6000 RPM, 490 ft-lbs @ 3800 RPM. So I'll probably going with something close to this.
                    1969 Riverside Gold Coupe, L71, 14,000 miles. Top Flight, 2 Star Bowtie.

                    Comment

                    • Jack C.
                      Frequent User
                      • June 30, 1984
                      • 48

                      #40
                      Re: 1966 427 425HP Valve Clearances

                      Originally posted by Chris Hewitt (33863)
                      For reference, the Chevy Performance catalogue, which contains all their crate motors etc., has the ZZ427/480, which is marketed as a "modern take on the classic L88". It has 10.0:1 compression, oval port aluminum heads, and the cam is a hydraulic roller, 224/234 with 527/544 ex lift. LSA not listed. 480HP @ 6000 RPM, 490 ft-lbs @ 3800 RPM. So I'll probably going with something close to this.
                      Chris - You are a couple of steps ahead of me. In my research of hydraulic roller cams, a general consensus I was getting was that they are designed more for racing and therefore may not have longevity for street use. I know, everyone has a theory, but one knowledgeable person I trust told me the hydraulic roller cams were good for hard racing but not good for a lot of idle time. I thought that was one of the main reasons to go with a roller, which made me think of my friend who just recently bought a 502 crate engine for a large work truck from the catalog you cited, built by GM with a hydraulic roller and a warranty. I just asked him this week what was in that engine for a cam and why would't there be a similar modern version that could be used for my engine. He mentioned the catalog and we have not referenced yet but will be shortly. Thanks for you input.

                      Comment

                      • Chris H.
                        Very Frequent User
                        • April 1, 2000
                        • 837

                        #41
                        Re: 1966 427 425HP Valve Clearances

                        Jack, whoever told you roller cams aren't for the street has been smoking something for a very long time. OEMS stopped using flat tappets in the 80s. Main benefits include reduced friction (mpg/horsepower) and reliability (no more worn out cam lobes).

                        Continue doing your own research. All the major cam companies have tech support who will give you recommendations. You need engine size, bore, stroke, compression ratio, car weight, manual or auto, tire size, etc. Crower did this for me recently.
                        1969 Riverside Gold Coupe, L71, 14,000 miles. Top Flight, 2 Star Bowtie.

                        Comment

                        • Chris H.
                          Very Frequent User
                          • April 1, 2000
                          • 837

                          #42
                          Re: 1966 427 425HP Valve Clearances

                          Jack, your friend may have been referring to "solid" roller versus "hydraulic" roller. Yes solid rollers are generally used for racing (6500+rpm) and have aggressive profiles that require big spring pressures etc. For the street, generally, hydraulic is more appropriate. That being said, I know guys who run solid rollers on the street just so they can hear the ticking.
                          1969 Riverside Gold Coupe, L71, 14,000 miles. Top Flight, 2 Star Bowtie.

                          Comment

                          • Joe L.
                            Beyond Control Poster
                            • February 1, 1988
                            • 43193

                            #43
                            Re: 1966 427 425HP Valve Clearances

                            Originally posted by Chris Hewitt (33863)
                            Jack, whoever told you roller cams aren't for the street has been smoking something for a very long time. OEMS stopped using flat tappets in the 80s. Main benefits include reduced friction (mpg/horsepower) and reliability (no more worn out cam lobes).

                            Continue doing your own research. All the major cam companies have tech support who will give you recommendations. You need engine size, bore, stroke, compression ratio, car weight, manual or auto, tire size, etc. Crower did this for me recently.

                            Chris and Jack------


                            Yes, and for example, Corvettes have had hydraulic roller cams since the 1987 model year.

                            Want the "ticking" sound? Well, if one has a small block all you have to do is to find a GM #10168506 hydraulic roller cam. This camshaft was used for 1992 LT1's. It makes just about the same "ticking" sound as a mechanical lifter cam. That's why GM slightly revised the profile for the 1993 model year to eliminate the "ticking" and assigned new part number 10224241. Of course, in a Gen I small block you'll have to use a cam button for thrust control, a melonized distributor gear, and retrofit hydraulic roller lifters (with bar type anti-rotation control). One will have a hard time finding a GM #10168506, though, as it was discontinued in July, 1997 and replaced by the 10224241.
                            In Appreciation of John Hinckley

                            Comment

                            • Jack C.
                              Frequent User
                              • June 30, 1984
                              • 48

                              #44
                              Re: 1966 427 425HP Valve Clearances

                              Here's the damage - #2 Intake, #5 Intake, and #6 Intake all failed. There is a lot of metal off the bottom of these lifters that had to go somewhere. I have not pulled down oil pump or checked bearings yet. It's hart to see in the pics but to me, the lifters look worse than the cam. Is it the chicken or the egg? I don't know. It appears the lifters may have failed first, stopped spinning, then took the cam out.Lifters 1.jpgLifters 2.jpgCam 2 Intake.jpgCam 5 and 6 Intakes.jpg

                              Comment

                              • Chris H.
                                Very Frequent User
                                • April 1, 2000
                                • 837

                                #45
                                Re: 1966 427 425HP Valve Clearances

                                Jack wow that’s pretty catastrophic. You are correct all that metal is now everywhere in your engine. That’s what prompted my rebuild. In my case I found wiped crank and rod journal bearings and due to I believe plugged oil passages from cam lobe material. Catastrophe was imminent and I consider myself lucky I didn’t lose the block.
                                1969 Riverside Gold Coupe, L71, 14,000 miles. Top Flight, 2 Star Bowtie.

                                Comment

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